Lead recovery from metallurgical slag by flotation Paulo F. A. Braga, João A. Sampaio, Carlos A. M. Baltar, Arnolfo M. Coelho, João A. F. Nunes

Brazil does not have a primary production of refined metallic lead. The whole production is based upon the recycling of automotive, industrial and telecommunication batteries. In 2010 the battery recycling industry produced 115,000 t of metallic lead from 2 nd production. Moura is the largest recycler/ manufacturer of batteries in Brazil ( units/y). INTRODUCTION

Operated at 90% efficiency (the ratio of the number of recycled batteries and the number of new batteries produced). With the increase in price of metallic commodities such as lead, several studies were carried out, aiming to: minimize the loss of this metal in the industrial processes or; for an additional recovery of the lead from metallic slags. INTRODUCTION

Recycling process starts with the removal of metallic parts such as connectors and screws and subsequently with the reduction of the battery scrap and separation of the plastic casing from the lead grates and lead paste. Lead paste follows the process of separation, casting, refining and manufacturing of new batteries. Plastic is recovered and reused in the production of casing and cover for the new batteries. Acid solution is neutralized by lime or limestone. INTRODUCTION

A typical automotive battery scrap contains: INTRODUCTION 32% Pb 3% PbO 17% PbO 2 36% PbSO 4 The main reactions of the metallurgical processes are: 2PbSO 4 + Na 2 CO 3 + Fe + 9C → 2Pb + FeS.Na 2 S + 9CO + CO 2 (1) PbO 2 + C → CO + PbO (2) 2PbO + C → CO 2 +2Pb (3) PbSO 4 + 2C → PbS + 2CO 2 (4)

The present research work aimed to study the flotation process on pilot scale for the recovery of lead from metallurgical slags rising from the recycling process of automotive batteries. There were also several tests carried out in gravity concentration equipment with the purpose of assessing this process route for the recovery of lead concentrate. OBJECTIVE

Chemical analysis of the slag sample: Compounds Grade (weight %) Compounds Grade (weight %) Compounds Grade (weight %) Cr 2 O K2OK2O0.21ZnO0.80 TiO P2O5P2O5 0.28CaO1.20 CuO0.12BaO0.31SiO MnO0.14Cl0.66Na 2 O4.37 Al 2 O SnO PbO16.90 Fe 2 O SO METHODOLOGY X-ray diffraction (XRD): metalic lead, magnetite (Fe 3 O 4 ), hatrurite (Ca 3 SiO 5 ), galena (PbS); jamesonite (Pb 4 FeSb 6 S 14 ) and cotunnite (PbCl 2 ).

Nominal aperture size (µm) Weight (%)Pb Grade (%) 3, , , Average Screen size distribution and lead grade per size fraction. METHODOLOGY

Equipments: jaw crushers vibrating screen conditioners reagent feeder flotation cells type Denver nº 7 Sub-A Wilfley laboratory concentrating table Humphreys spiral concentrator crossflow 2x4. METHODOLOGY Metering pumps Flotation Cells Flotation Circuit potassium amyl xanthate ( PAX) – collector; methyl isobutyl carbinol (MIBC) - frother; sulphuric acid (H 2 SO 4 ) - pH adjuster. Reagents:

Sample Preparation METHODS Slag of lead (25 t) Jaw crusher (1”) Screening (2 mm) Jaw crusher (1/2”) Screening (2 mm) Hammer mill (5 mm) Screening (2 mm) Screening (-0,7 mm) Homogenization pile Discard (+ 0,7 mm)

Flotation Procedure Slag : µm (size); pH: 8 (sulphuric acid); 50 kg/h: slag (flow rate); 150 g/t: PAX (collector); 50 g/t: MIBC (frother). Reagent system and operating conditions in laboratory scale for flotation tests were previously defined by Baltar (2005). conditioner tank Bomba pump rougher Concentrate feed tank dosage pump flotation cell collector: potassium amyl xantate frother: MIBC Tailings METHODS

Weight recovery (%)Pb (%)Pb recovery (%) Rougher concentrate Rougher tailings Feed Flotation test RESULTS

Wilfley laboratory shaking table test Products Bulk sample Pb (%)Pb recovery (%) Concentrate Middlings Tails Feed17.2- Products Rougher concentrate Pb (%)Pb recovery (%) Concentrate Middlings Tails Feed48.8- RESULTS

ProductsWeight recovery (%)Pb (%)Pb recovery (%) Concentrate Tailings Feed Crossflow hydraulic classifier test (elutriation test) Spiral concentrator test ProductsMass recovery (%)Pb (%)Pb recovery (%) Concentrate Tailings Feed RESULTS

Main composition of lead metallurgical slag is: 16.9% PbO, 29.8% SO 3 and 41.6% Fe 2 O 3. The main mineralogical species are: magnetite (Fe 3 O 4 ); hatrurite (Ca 3 SiO 5 ); galena (PbS); jamesonite (Pb 4 FeSb 6 S 14 ); cotunnite (PbCl 2 ) and metallic lead. The fine fraction -37  m represented 51.9% of the bulk sample and contained 12.61% of lead. FINAL REMARKS

The flotation at pilot scale produced lead concentrates at 48.8% Pb and a concentration ratio of 2 and 80% recovery. These results were obtained after fine fraction removal (-37 μm); Shaking table tests produced a concentrate at high grade, 55.9% Pb, and 37.2% recovery from the bulk sample; Reprocessing the rougher flotation concentrate in the shaking table produced a final concentrate at 72.3% Pb, concentration ratio of 1.5 and 56.5% recovery. FINAL REMARKS

ACKNOWLEDGMENTS

THANK YOU MUCHAS GRACIAS